Bearing and sealing means



Dec. 5, 1967 L WE ET AL 3,356,292

BEARING AND SEALING MEANS Filed Oct. 4, 1965 2 Sheets-Sheet 1 INVENTORS Fee /77. Ezewer gxw ATTORNEY Dec. 5, 1967 BREWER ET AL 3,356,292

BEARING AND SEALING MEANS ATTORNEY United States Patent 3,356,292 BEARING AND SEALING MEANS Lee M. Brewer and Robert P. Rohde, Saginaw, Mich., as-

signors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 4, 1965, Ser. No. 492,821 7 Claims. (Cl. 230-157) This invention relates to means for sealing the working chamber of a rotary mechanism such as a pump for reducing the frictional losses in the rotary mechanism. More particularly, this invention relates to a vane type rotary mechanism which has a highly efiicient arrangement providing a bearing in and sealing the area between the vane and its supporting slot in the rotor.

In the recent past, increasing emphasis has been placed on reducing the proportion of unburned constituents, such as unburned hydrocarbons and carbon monoxide, present in the exhaust gases emitted from automotive engines. One of the most effective arrangements devised to accomplish this reduction is the Air Injector Reactor system. In this system, an engine driven pump injects a stream of air into the flow of hot exhaust gases as they are emitted from the engine combustion chambers. Utilizing the heat of the exhaust gases, the injected air supports additional burning of the exhaust gases in the engine exhaust passages to reduce the proportion of unburned constituents in the exhaust gas.

The requirements imposed upon the pump used to supply the air in the Air Injector Reactor system are quite stringent; for example, the pressure and the rate of the air flow from the pump must be carefully controlled over a wide range of engine speeds for optimum reduction of exhaust emissions. It has been discovered that a semiarticulated vane pump is a very efiicient and economical type for such an application.

In such a pump, however, the vane extends into the working chamber through a slot in the rotor. This slot must be sealed in order that the pressure developed in the working chamber is not lost through the rotor. On the other hand, the vane must reciprocate in and out of the slot, and the usual sealing arrangement creates a source of friction tending to reduce the efiiciency of operation of the pump. Such frictional losses cannot be overcome by oils and greases used in conventional lubricating systems, because during operation those lubricants would be gradually vaporized and emitted from the pump. The pump would then become another source for unburned hydrocarbons. I

This invention provides a bearing and sealing arrangement which reduces the frictional loss to improve the efficiency of pump operation and which additionally seals the working chamber to increase the volumetric efiiciency of the pump. In addition, the bearing and sealing arrangement provided by this invention has an extended operational life, thus improving the durability of the pump.

The details as well as other objects and advantages of this invention appear in the following description and in the drawings in which:

FIGURE 1 illustrates an internal combustion engine provided with a pump which injects air into the exhaust system;

FIGURE 2 is a vertical sectional view through the pump illustrating the vane mounting arrangement;

FIGURE 3 is a sectional view along line 3-3 of FIG- URE 2 illustrating the arrangement of the rotor and vanes within the housing; and

FIGURE 4 is a sectional view along the line 44 of FIGURE 3 illustrating the location of notches provided between the working chamber and its inlet and outlet.

Referring first to FIGURE 1, an internal combustion engine E is provided with a carburetor C and an air filter 3,356,292 Patented Dec. 5, 1967 F. An air pump 10 is secured to engine E by a bracket 12 and is driven by engine E through a belt 14. Air pump 10 has an inlet hose 16 through which clean air is drawn from air filter F and an outlet hose 18 through which air is delivered to an air manifold 20. Air manifold 20 has a series of injection tubes 22 through which air is injected into the stream of exhaust gases adjacent the combustion chamber exhaust valves.

Referring now to FIGURES 2 and 3, air pump 10 has a concave housing 24 closed by a cover plate 26. As shown in FIGURE 3, the interior wall 23 of housing 24 is of circular cross section. A rotor 30, disposed in housing 24 on-an axis eccentric to the axis of the housing, has an exterior wall 32 of circular cross section which is tangent the interior wall 28 of housing 24 at its lowermost point to provide a stripping land 34.

Pump housing 24 is made of aluminum and rotor 30 of cast iron so that as the temperature of the pump increases during operation, housing 24 will expand faster than rotor 30 to prevent frictional contact between these two parts.

The interior wall 28 is recessed on opposite sides of the stripping land 34 to form an inlet area 36 and an outlet area 38. Inlet and outlet areas 36 and 38 extend axially the entire length of the pump and are provided at one end with fittings 40 to which the inlet and outlet hoses 16 and 18 are secured.

A particular advantage is achieved by locating the inlet and outlet areas 36 and 38 at the bottom of the pump since any moisture tending to condense in the pump will drain into these areas. Should the pump be mounted in an inverted position, the moisture would drain to another portion of the housing. This moisture would interfere with pump operation were it to freeze.

A shaft 42 is secured in cover plate 26 and extends into housing 24 concentrically with the interior wall 28. Three pairs of bearing supporting hubs 44 are positioned on shaft 42, each pair supporting a vane 46 which extends closely adjacent the interior wall 28 of the housing 24.

Rotor 30 surrounds shaft 42 and hubs 44 and is provided with slots 48 through which the vanes 46 extend.

Rotor 30 has a shaft 50 extending through housing 24 to a pulley 52 driven by belt 14. As rotor 30 is driven (clockwise as viewed in FIGURE 3), vanes 46 are swept through the crescent-shaped working chamber 54 to draw air from inlet 36 and direct a pressurized stream of air through outlet 38. Stripping land 34 prevent leakage of air between outlet 38 and inlet 36, increasing the efficiency of the pump.

As shown in FIGURES 3 and 4, the interior wall 28 of housing 24 is provided with a notch 56 leading from the inlet area 36 to the working chamber 54 and a notch 58 leading from the working chamber 54 to the outlet area 38. Notches 56 and 58 prevent a sudden change in pressure as vanes 46 pass the inlet and outlet areas 36 and 38.

Each vane 46 is sealed in its corresponding slot 48 in rotor 30 by a pair of carbon sealing strips 60 and 62 positioned in grooves 64 opening into the slots 48. Referring to FIGURE 3, it will be appreciated that as rotor 30 is driven clockwise by belt 14, sealing strips 60 provide the thrust to drive vanes 46. Sealing strips 62 are backed by conventional leaf springs 66 which bias strips 62 against vanes 46. Sealing strips 60 and 62 thus cooperate to prevent air flow from the working chamber 54 through slots 48 into the interior portion of rotor 30.

We have discovered that a vane composed of a thermosetting plastic resin reinforced with fiberglass or asbestos is highly compatible with the carbon sealing strips 60 and 62 and resists wear to provide a highly durable pump. An epoxy resin and woven glass cloth laminate, available under the trademark Insurok, grade T-53 6, has been found to be very satisfactory as a vane material. This material has a low rate of thermal expansion which is necessary so that as the pump heats during operation, the vane does not frictionally contact the housing. In addition, this material has a low density which reduces the centrifugal force on the shaft 42. Furthermore, the material has a low water absorption ehararteristie providing stable vane dimensions during operation in humid weather. In addition, this vane material has a high strength which is retained throughout the wide range of pump operating temperatures.

It will be appreciated that as rotor 30 and vanes 46 are driven, each vane 46 will oscilalte through its associated slot 48. Carbon strips 60 and 62 contact vanes 46 to provide a bearing surface for such oscillation. Despite such oscillation against the carbon strips 60 and 62, the reinforced thermosetting plastic resin of vanes 46 provides a highly durable pump component.

We claim:

1. A rotary mechanism including a hollow outer body having an internal peripheral wall, an internal body positioned within said outer body and having an external peripheral wall radially spaced from at least portions of said internal peripheral wall to form a working chamber, said inner and outer bodies being relatively rotatable, one of said walls having an axially extending recess, a vane extending radially from said recess into said working chamber to create pressure variations therein upon relative rotation of said bodies, the surface material of said vane comprising a reinforced thermo-setting plastic resin, and means in said recess spacing said vane from said body, said means having a carbon surface bearing against said vane surface.

2. The mechanism of claim 1 wherein said vane surface material comprises a thermo-setting plastic resin reinforced with a substance selected from glass and asbestos.

3. The mechanism of claim 2 wherein said thermosetting plastic resin is an epoxy.

4. The mechanism of claim 2 wherein said substance is a glass cloth.

5. The mechanism of claim 1 wherein said vane comprises a woven glass cloth and epoxy resin laminate.

6. A rotary pump including a housing having axially spaced end walls connected by a cylindrical internal peripheral wall forming a cavity, a rotor positioned within said cavity and having end walls adjacent the housing end walls, said rotor having axial extensions supporting each end of said rotor in said housing end walls for rotation relative thereto, said rotor having an axis parallel to and spaced from the axis of said cavity and having a cylindrical external peripheral wall radially spaced from portions of said internal wall to form a working chamber, the axially extending portion of said internal wall most closely adjacent said rotor forming a stripping land, said working chamber having an inlet and an outlet adjacent and on opposite sides of said stripping land, a shaft supported in one of said housing end walls and extending concentrically into said cavity, said shaft being surrounded by said rotor, a plurality of radially extending vanes mounted for rotation upon said shaft, the composition of said vanes comprising a reinforced thermo-setting plastic resin, said rotor having slots through which said vanes extend into said working chamber, said rotor and vanes being adapted upon rotation to direct a fluid stream through said working chamber from said inlet to said outlet and to increase the pressure in said fluid stream, said slots having axially extending recesses in the sides thereof, and means sealing said vanes in said slots and spacing said vanes from said rotor comprising axially extending carbon strips positioned in said recesses and bearing against said vanes.

7. An air pump adapted for use in a system for supplying air to the stream of hot exhaust gases emitted from an internal combustion engine, said air pump including a housing having axially spaced end walls connected by a horizontally extending cylindrical internal peripheral wall forming a cavity, a hollow rotor positioned within said cavity and having a horizontal axis parallel to and spaced from the axis of said cavity, said rotor having end walls adjacent the housing end walls and having a drive shaft concentric with said rotor extending axially from one end wall of said rotor through one end wall of said housing, said drive shaft being adapted to support and rotate said rotor within said housing, said rotor having a cylindrical external peripheral wall radially spaced from portions of said internal wall to form a crescentshaped working chamber, said housing internal wall having an axially extending portion tangent the lowermost portion of said rotor and forming a stripping land, said internal wall having a pair of recesses adjacent and on opposite sides of said stripping land forming an inlet and an outlet for said working chamber, a mounting shaft secured in the other end wall of said housing and extending concentrically into said cavity, said rotor surrounding said mounting shaft, a plurality of radially extending vanes mounted for rotation upon said mounting shaft, the composition of said vanes comprising a woven glass cloth and epoxy resin laminate, said rotor having slots through which said vanes extend into said working chamber, said rotor and vanes being adapted upon rotation to direct an air stream through said working chamber from said inlet to said outlet and to increase the pressure in said air stream, said internal wall having notches leading from the recess forming the inlet and leading into the recess forming the outlet to achieve a gradual increase in the air stream pressure, and a pair of carbon sealing strips for each vane, said slots having axially extending recesses On each side of said vanes in which said strips are positioned, one of said strips transmitting thrust from said rotor to the vane, the other of said strips being spring biased against the vane, said strips additionally spacing said vanes from said rotor and providing a bearing surface for radial reciprocation of said vanes relative to said rotor.

References Cited UNITED STATES PATENTS Re. 24,932 1/1961 Davey 91-119 977,338 11/1910 Sqnier 230-157 1,836,037 12/1931 Musselwhite 230157 2,001,011 5/1935 Brown 103-144 2,071,799 2/1937 Mabille 103144 2,243,899 6/1941 Fuleher 230157 2,470,656 5/1949 Shorrock 230l57 2,899,940 8/1959 Gibbs et a1. 91-119 2,952,249 9/1960 Conover 91-119 3,191,852 6/1965 Kratz et al. 91-419 HENRY F. RADUAZO, Primary Examiner.

W. J. GOODLIN, Examiner. 

1. A ROTARY MECHANISM INCLUDING A HOLLOW OUTER BODY HAVING AN INTERNAL PERIPHERAL WALL, AN INTERNAL BODY POSITIONED WITHIN SAID OUTER BODY AND HAVING AN EXTERNAL PERIPHERAL WALL RADIALLY SPACED FROM AT LEAST PORTIONS OF SAID INTENAL PERIPHERAL WALL TO FORM A WORKING CHAMBER, SAID INNER AND OUTER BODIES BEING RELATIVELY ROTATABLE, ONE OF SAID WALLS HAVING AN AXIALLY EXTENDING RECESS, A VANE EXTENDING RADIALLY FROM SAID RECESS INTO SAID WORKING CHAMBER TO CREATE PRESSURE VARIATIONS THEREIN UPON RELATIVE ROTATION OF SAID BODIES, THE SURFACE MATERIAL OF SAID VANE COMPRISING A REINFORCED THERMOSETTING PLASTIC RESIN, AND MEANS IN SAID RECESS SPACING SAID VANE FROM SAID BODY, SAID MEANS HAVING A CARBON SURFACE BEARING AGAINST SAID VANE SURFACE. 